The present invention relates to a stapler apparatus which binds media (a sheet bundle), such as a plurality of documents printed with a copying machine, a printer, or a composite of machines thereof, etc., with staples, particularly to an improved staple cartridge used in the stapler apparatus.
Such stapler apparatuses conventionally are mounted with a staple cartridge comprising a storage portion for storing rolled sheets of rolled bands of staples that are linked to form a sheet, or stacks of sheets of staples. The staple sheets in the staple cartridge are pulled out, and are drawn sequentially to a staple driving position and the staples are then driven into media for binding.
Staple cartridges mounted to the stapler apparatus are equipped with a return prevention means to abut the staple linking portion of the stable band drawn out with a return stopper pawl so that the staple band pulled out from the storage portion does not return back into the storage portion.
However, the return stopper pawl of the return prevention means abuts the staple linking portion on one location with the paired left and right pawl or to increase the abutting force thereof, a return stopper pawl is disposed in front and back in the direction of staple band pull-out disposed to abut the staple linking portion on two locations with the paired left and right pawl simultaneously.
However, there are situations where the staple linking portion cannot be securely abutted to stop because of variations in the width dimensions of the staples or the gap of the staples that configure the staple band, caused by the adhesive, or the variations in the staple cartridge mounting position, the variations in the gap in the staple linking portion that is abutted by the return stopper pawl from the staple that has been drawn to the driving position, the variation thereof causing the return stopper pawl to ride up on the surface of the staple.
In the state where the return stopper pawl rides up on the surface of the staple, the staple band backs up an amount near the width of the staple, at its maximum to move to be abutted. This results in the staple that had already been drawn to the driving position returning back and causing a discrepancy in its position. This is one of the causes of the binding problems of the mis-driving or biting of staples.